Study On The Combined Toxicity Of HBE Cells Induced By Radon In Combination With Sodium Arsenite

Objective: Determine the type of effects of radon in combination with sodiumarsenite on HBE cells, study the effects to oxidate damage and DNA damage.Methods:(1) The HBE cells were exposed to various concentrations of radon(20000Bq/m3,0～75min), sodium arsenite (0～50000μmol/L) and combination groups.The cell viability was tested by Cell Counting Kit-8(CCK-8). Through themedian-effect equation Comput HBE cells exposure to Radon in different time anddifferent doses of sodium arsenite combination index (CI).(2) HBE cells were exposedto various concentrations of radon (20000Bq/m3,10min;20000Bq/m3,20min and20000Bq/m3,40min) and sodium arsenite (1.5μmol/L,3μmol/L and6μmol/L). Thereactive oxygen species (ROS) level，the malondialdehyde (MDA) and the superoxidismutase (SOD) content in HBE cells were detected respectively. Comet assay wasapplied for quantitative analysis of DNA damage in HBE cells induced by sodiumarsenite.(3) HBE cells were exposed to radon and sodium arsenite alone andco-exposure after24hours. Expression of γH2AX and Rad51were determined byWestern blotting.Results:(1) Radon and sodium arsenite alone or in combination inhibited thegrowth of HBE cells. Computed using median-effect principle,(CI)=0.41, CI<1indicating that radon and sodium arsenite had synergistic effect.(2) Compared withcontrol group, exposure to radon and sodium arsenite alone induced the level of ROSand the content of MDA signifiantly elevated (P<0.05), while the content of SOD wassignificantly decreased (P<0.05). Besides, they show a dose-response relationship withexposure time of radon. Respectively under the conditions with radon exposure timeconstant and sodium arsenite dose constant, compared with radon and sodium arsenitealone, co-exposure to radon and sodium arsenite induced the level of ROS and thecontent of MDA signifiantly increased (P<0.05), while the content of SOD wassignificantly decreased (P<0.05).(3) Comet assay: Compared with control group, exposure to radon and sodium arsenite alone could significantly increase tail DNA%(P<0.05), tail moment (P<0.05) and Olive tail moment (P<0.05) in HBE cells. Besides,there was a dose response relationship between radon exposure time, sodium arsenitedose and DNA damage. Respectively under the conditions with radon exposure timeconstant and sodium arsenite dose constant, compared with radon and sodium arsenitealone, co-exposure to radon and sodium arsenite induced tail DNA%tail moment andOlive tail moment signifiantly increased (P<0.05).(4) The expression of γH2AX andRad51were confirmed to show a dose response relationship with exposureconcentration of sodium arsenite. Co-exposure to radon and sodium arsenite induced theexpression of γH2AX and inhibited the expression of Rad51, compare with radon andsodium arsenite alone.Conclusion:1.The combination of radon and sodium arsenite had a synergisitic growthinhibition effect on HBE cells.2.The growth inhibition effects were induced by causing severe oxidate damageand DNA damage.